1. Field of the Invention
The present invention generally relates to a paper conveyance device, a fixing device, and an image forming apparatus, and, in particular, to a paper jam removal mechanism.
2. Description of the Related Art
Image forming apparatuses such as copiers, facsimiles, printers, and printing machines that use the electrophotography technology finish copying or printing by fixing an unfixed image composed of unfixed toner that has been transferred and carried on paper that is a recording medium.
Inside an image forming apparatus, provided are conveyance paths for conveying paper, one of which conveys paper that has been passed through a fixing device to a discharging unit. The conveyance path includes conveyance guides disposed such that the conveyance guides face the front surface and the back surface of a sheet of paper, respectively. When a sheet of paper moving through the conveyance path causes a conveyance failure such as a paper jam, the sheet needs to be removed. In particular, a sheet that has passed through the fixing device may curl in some cases because of heat at the fixing process. The leading end of the sheet abuts on a separation claw because of the curling and the sheet is not separated from the fixing device in some cases, whereby conveyance failure may occur.
In order to remove a sheet from a conveyance path to recover from the conveyance failure, for example, a technology has been developed as in Japanese Patent Application Laid-open No. 2013-186287. The technology discloses an image forming apparatus including a display portion that indicates a location at which conveyance failure is occurring. In accordance with the indication, a user opens an outer cover at the location and then opens a conveyance cover to expose the conveyance path to outside.
Another technology has also been developed as in Japanese Patent Application Laid-open No. 2008-292642, that discloses an image forming apparatus including a fixing cover open-close mechanism. With the mechanism, a conveyance guide is opened in association with an open-close movement of an outer cover of the image forming apparatus.
When an image forming apparatus includes a configuration for removing a sheet that causes a paper jam, the configuration is complicated if the image forming apparatus includes a configuration for displaying where the paper jam is occurring or an open-close mechanism with which a conveyance cover is operated in association with an open-close operation of an outer cover. In particular, when the image forming apparatus includes the configuration for displaying where a paper jam is occurring, the image forming apparatus needs extra wiring for a display member. Parts disposed near the fixing device are largely affected by heat compared to the other parts of the image forming apparatus, so that a heat-resistant processing or heat-insulating structure is needed for the parts such as wiring harnesses. Consequently, the structure becomes more complicated and the production cost increases. When the image forming apparatus includes an open-close mechanism that operates a conveyance guide in association with the movement of the outer cover, the user cannot see where to remove the misconveyed sheet very well but can open the conveyance guide without touching it. In the same manner as in the case of providing a display portion for the image forming apparatus, the configuration of the open-close mechanism becomes more complicated and production cost such as assembly cost increases. These problems occur not only in the paper conveyance configuration of the fixing device but paper conveyance configurations of other devices, and also occur in an image forming apparatus that forms images by using a technology different from electrophotography.
In view of the above-mentioned conventional problems, there is a need to provide a paper conveyance device, a fixing device, and an image forming apparatus that facilitate the open-close operation of a conveyance guide without a complicated structure or a cost increase.